High volume industrial painting of motor vehicles, appliances, furniture and other large items of manufacture is frequently carried out via fairly complex paint delivery systems. These systems include a number of paint delivery lines, spray heads and nozzles, tanks, pumps and the like. These paint delivery systems must be purged on a regular basis for purposes of maintenance, and when paint types or colors are changed. Purging includes the step of flushing the system with a purge solvent composition. This purge solvent should operate to remove paint residues and solvate dehydrated paint films. The purge solvent must be compatible with the paints which are employed in the system; and increasingly, industry is turning to water-based paints.
Hence, there is a need for purge solvents which are compatible with water-based paints and which can solubilize dehydrated films of the water-based paints, which films are generally water insoluble. Paint delivery systems frequently include components manufactured from reactive materials such as aluminum or the like; hence, purge compositions should be non-reactive towards system components. In addition, purge compositions should be low in volatile organic compounds (VOC) and should be low in toxicity and flammability. Also, purge compositions should be active at room temperature and preferably should be low in cost.
A number of purge compositions for water-based paints are known in the prior art. One purge composition which is presently employed includes glycol ethers such as propylene glycol normal propyl ether, butyl cellosolve, and the like together with dimethylethanolamine and water. This composition functions as a purge solvent for water-based paints; however, it must be used at elevated temperatures, which complicates its use and handling. Thus, there is a need for a purge solvent composition which is compatible with water-based paints and which can readily solubilize dehydrated residues of such water-based paints at room temperature.